The present invention relates to CT systems and more particularly to methods and systems for balancing CT gantry members.
Computed Tomography (“CT”) systems are in wide use today. The CT systems take X-ray images of objects or persons in order to provide scientific and/or medical information. In general, CT systems include a large gantry mechanism positioned in a housing with an annular opening in which the object or person is positioned. The gantry mechanism includes a rotating base member on which an X-ray tube and detector plate are mounted. As the base member rotates and the object or person is moved along the axis of rotation, X-ray images are taken for later analysis.
The rotating base member typically has other system components mounted on it, such as a heat exchanger and generator. The X-ray tube, detector plate, and other components rotate with the base member. It is important to balance the rotating base member so that it revolves uniformly and provides satisfactory, high quality images.
Imbalance of the rotating portion of a CT gantry results in an oscillatory motion of the entire gantry mechanism at a frequency of once per revolution. This motion is detrimental to the quality of the images and can generate artifacts when the motion is increased above a certain threshold. Typically, CT gantry mechanisms are balanced in the factory where the CT systems are built and calibrated, before they are shipped to their ultimate destinations. The CT systems are also balanced in the field, typically when components are replaced for service, such as a new X-ray tubes. The field balance is particularly important in order to assure accurate performance of the CT system. At the present time, however, methods and systems used to balance gantry mechanisms in the field have shortcomings. Thus, there is a need for improved systems and methods for balancing CT gantry mechanisms, particularly for balancing the mechanisms in the field.